An Unusual Succulent In The Appalachian Understory: Light Capture And Drought Tolerance In Sedum ternatum

Sedum ternatum is a succulent plant native to the Appalachian forest understory. This study first examines its use of understory sunlight throughout the year by measuring field photosynthesis, growth, and pigment production. Leaf thickness, succulence, and stomatal density are quantified. The thesis also reports the results of two greenhouse experiments. One experiment tested drought tolerance in S. ternatum, including its expression of Crassulacean Acid Metabolism (CAM). The other compared morphology and chlorophyll production between plants grown under high and low light. The study concludes that the thick S. ternatum leaf accomplishes most of the plant’s carbon gain in the sunny windows of spring and fall, when the tree canopy is absent. The thick leaf and CAM expression also facilitate plant survival during the type of short-term water deprivation encountered in the drier understory microhabitats (boulders, south-facing slopes, eroding soil) often colonized by S. ternatum.